U.S. patent application number 12/327645 was filed with the patent office on 2009-06-11 for fixing device.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Satoshi HIMENO.
Application Number | 20090148212 12/327645 |
Document ID | / |
Family ID | 40721831 |
Filed Date | 2009-06-11 |
United States Patent
Application |
20090148212 |
Kind Code |
A1 |
HIMENO; Satoshi |
June 11, 2009 |
FIXING DEVICE
Abstract
An embodiment provides plural rollers that rotate by sliding
contact with a sheet of paper on a fixing guide. The sheet of paper
supporting a toner image is guided toward a nip position of a
fixing roller along the rollers of the fixing guide. At guiding by
the fixing guide, the sheet of paper is not contact with a guide
plate.
Inventors: |
HIMENO; Satoshi; (Shizuoka,
JP) |
Correspondence
Address: |
PATTERSON & SHERIDAN, L.L.P.
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON
TX
77056
US
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
Tokyo
JP
TOSHIBA TEC KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
40721831 |
Appl. No.: |
12/327645 |
Filed: |
December 3, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61012773 |
Dec 10, 2007 |
|
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|
Current U.S.
Class: |
399/400 |
Current CPC
Class: |
G03G 15/2028
20130101 |
Class at
Publication: |
399/400 |
International
Class: |
G03G 15/00 20060101
G03G015/00 |
Claims
1. A fixing device comprising: a fixing member that nips and
carries a recording medium supporting an image and fixes the image;
and a guide member having plural rotating members provided in
plural rows in a traveling direction of the recording medium from a
transfer position where the image is transferred onto the recording
medium toward the fixing member and in plural rows in a width
direction of the recording medium, and slidingly rotating in
contact with the recording medium.
2. The device according to claim 1, wherein the plural rotating
members are arranged so that a surface in contact with tops of the
plural rotating members is in parallel to the traveling direction
of the recording medium.
3. The device according to claim 1, wherein the guide member
supports the plural rotating members by a supporting member in
parallel to the traveling direction of the recording medium and the
plural rotating members are protruded from a supporting surface of
the supporting member.
4. The device according to claim 3, wherein the surface in contact
with the tops of the plural rotating members is in parallel to the
supporting surface.
5. The device according to claim 3, wherein the height to which the
plural rotating members are protruded from the supporting surface
is 1 mm or less.
6. The device according to claim 3, wherein the supporting member
further comprising a rib in parallel to the traveling
direction.
7. The device according to claim 6, wherein the height to which the
plural rotating members are protruded from the supporting surface
is higher than a height of the rib.
8. The device according to claim 1, wherein the plural rotating
members have roller shapes.
9. The device according to claim 1, wherein the plural rotating
members have star wheel shapes.
10. The device according to claim 1, wherein the plural rotating
members are formed by a fluorine material.
11. An image forming apparatus comprising: an image forming member
that forms an image on an image carrier; a transfer member that
transfers the image onto a recording medium; a fixing member that
nips and carries the recording medium and fixes the image; and a
guide member having plural rotating members provided in plural rows
in a traveling direction of the recording medium from the transfer
member toward the fixing member and in plural rows in a width
direction of the recording medium, and slidingly rotating in
contact with the recording medium.
12. The apparatus according to claim 11, wherein the transfer
member is a transfer roller member that nips and carries the
recording medium between the image carrier and itself.
13. The apparatus according to claim 11, wherein the plural
rotating members are arranged so that a surface in contact with
tops of the plural rotating members is in parallel to the traveling
direction of the recording medium.
14. The apparatus according to claim 11, wherein the guide member
supports the plural rotating members by a supporting member in
parallel to the traveling direction of the recording medium and the
plural rotating members are protruded from a supporting surface of
the supporting member.
15. The apparatus according to claim 14, wherein the surface in
contact with the tops of the plural rotating members is in parallel
to the supporting surface.
16. The apparatus according to claim 14, wherein the supporting
member further has a rib in parallel to the traveling
direction.
17. The apparatus according to claim 16, wherein the height to
which the plural rotating members are protruded from the supporting
surface is higher than a height of the rib.
18. The apparatus according to claim 11, wherein the plural
rotating members have roller shapes.
19. The apparatus according to claim 11, wherein the plural
rotating members have star wheel shapes.
20. The apparatus according to claim 11, wherein the plural
rotating members are formed by a fluorine material.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from provisional U.S. Application 61/012,773 filed on Dec.
10, 2007, the entire contents of which are incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention relates to a fixing device that fixes
toner images on recording media in a copier, printer, or the
like.
BACKGROUND
[0003] An image forming apparatus such as a copier or a printer
mounts a fixing device that nips and carries sheets of paper for
fixing. Such a fixing device allows sheets of paper to pass between
rollers of a heating roller and a pressing roller, for example, or
in a nip position direction formed between belts for the similar
roles and fixes toner images by applying heat and pressure to them.
A carrying guide that guides the sheets of paper to the nip
position conventionally uses a stationary flat plate of a metal
plate or mold. Alternatively, rollers are provided in part of such
a stationary flat plate. The carrying guide reliably feeds sheets
of paper to the nip position. Thereby, image blurring and paper
wrinkles are prevented at fixing.
[0004] However, in the conventional carrying guide, flying toner
and toner adhering to the back of the sheets of paper attach to the
flat plate part and gradually become deposited. Due to the toner
attached to and further deposited on the flat plate part, the
accuracy of the carrying guide to guide the sheets of paper becomes
lower and image blurring and paper wrinkles may be caused.
Alternatively, due to the toner attached to and further deposited
on the flat plate part, smudges on the back of paper or jamming may
be caused.
[0005] Accordingly, toner attachment to the carrying guide is
suppressed. After all, development of a fixing device with which
good fixed images without image blurring or paper wrinkles can be
obtained and smudges on the back of paper and jamming can be
prevented is designed.
SUMMARY
[0006] An aspect of the invention is to suppress toner attachment
to the carrying guide regardless of flying toner or toner adhering
to the back of sheets of paper. Good fixed images can be obtained
and smudges on the back of paper and jamming can be prevented.
[0007] According to embodiments, a fixing device includes a fixing
member that nips and carries a recording medium supporting an image
and fixes the image, and a guide member having plural rotating
members provided in plural rows in a travelling direction of the
recording medium from a transfer position where the image is
transferred onto the recording medium toward the fixing member and
in plural rows in a width direction of the recording medium, and
slidingly rotating in contact with the recording medium.
DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic configuration diagram showing an image
forming apparatus on which a fixing device of an embodiment of the
invention is mounted;
[0009] FIG. 2 is a schematic side view showing a fixing unit of the
embodiment of the invention;
[0010] FIG. 3 is a schematic perspective view showing a fixing
guide of the embodiment of the invention;
[0011] FIG. 4 is a schematic explanatory diagram showing the fixing
guide of the embodiment of the invention;
[0012] FIG. 5 is a schematic explanatory diagram showing
arrangement of rollers and ribs of the fixing guide of the
embodiment of the invention;
[0013] FIG. 6 is a schematic explanatory diagram showing star
wheels of a first modified example of the invention;
[0014] FIG. 7 is a schematic explanatory diagram showing a fixing
guide of a second modified example of the invention; and
[0015] FIG. 8 is a schematic explanatory diagram showing a fixing
guide of a third modified example of the invention.
DETAILED DESCRIPTION
[0016] As below, an embodiment of the invention will be described
in detail taking the accompanying drawings as examples. FIG. 1 is a
schematic configuration diagram showing a four-drum tandem color
copier 1 as an image forming apparatus of an embodiment. The color
copier 1 includes a scanner unit 2 and a paper discharge unit 3 in
the upper part. The color copier 1 has an image forming unit 11 as
a image forming member including four sets of image forming
stations 11Y, 11M, 11C and 11K of yellow (Y) magenta (M), cyan (C),
black (K) arranged in juxtaposition along the lower part of an
intermediate transfer belt 10 as an image carrier.
[0017] The image forming stations 11Y, 11M, 11C and 11K have
photoconductive drums 12Y, 12M, 12C and 12K, respectively. Around
the photoconductive drums 12Y, 12M, 12C and 12K, charging chargers
13Y, 13M, 13C and 13K, developing devices 14Y, 14M, 14C and 14K,
and photoconductor cleaning devices 16Y, 16M, 16C and 16K are
provided along the rotational direction of arrow m, respectively.
Exposure lights by a laser exposure device 17 are applied to parts
between the respective charging chargers 13Y, 13M, 13C and 13K to
the developing devices 14Y, 14M, 14C and 14K around the
photoconductive drums 12Y, 12M, 12C and 12K. When the exposure
light is applied, electrostatic latent images are formed on the
photoconductive drums 12Y, 12M, 12C and 12K, respectively.
[0018] The developing devices 14Y, 14M, 14C and 14K have
two-component developers containing respective yellow (Y) toner,
magenta (M) toner, cyan (C) toner or black (K) toner and carrier,
respectively. The respective developing devices 14Y, 14M, 14C and
14K supply toner to the electrostatic latent images on the
photoconductive drums 12Y, 12M, 12C and 12K, respectively.
[0019] The intermediate transfer belt 10 is hung with tension by a
backup roller 21, a driven roller 20 and first to third tension
rollers 22 to 24. The intermediate transfer belt 10 faces in
contact with the photoconductive drums 12Y, 12M, 12C and 12K. In
positions of the intermediate transfer belt 10 facing the
photoconductive drums 12Y, 12M, 12C and 12K, primary transfer
rollers 18Y, 18M, 18C and 18K for primary transfer of toner images
as the images formed on the photoconductive drums 12Y, 12M, 12C and
12K onto the intermediate transfer belt 10 are provided.
[0020] In a secondary transfer part as a transfer position
supported by the backup roller 21 of the intermediate transfer belt
10, a secondary transfer roller 27 as a transfer roller member and
as a transfer member is provided. In the secondary transfer part, a
predetermined secondary transfer bias is applied to the backup
roller 21. While a sheet of paper as a recording medium is nipped
and carried between the intermediate transfer belt 10 and the
secondary transfer roller 27, the toner image on the intermediate
transfer belt 10 is secondary-transferred thereon. After the
secondary transfer, the intermediate transfer belt 10 is cleaned by
a belt cleaner 10a.
[0021] A paper feed cassette 4 for feeding sheets of paper toward
the secondary transfer roller 27 is provided below the laser
exposure device 17. On the right side of the color copier 1, a
manual feed mechanism 31 for manually feeding sheets of paper is
provided.
[0022] A pickup roller 4a, a separating roller 28a, a carrying
roller 28b and a resist roller 36 are provided in a part from the
paper feed cassette 4 to the secondary transfer roller 27. A manual
paper feed pickup roller 31b and a manual feed separating roller
31c are provided in a part from a manual feed tray 31a of the
manual feed mechanism 31 to the resist roller 36.
[0023] A fixing unit 40 is provided at the downstream of the
secondary transfer part along the traveling direction of the sheet
of paper P. The fixing unit 40 has a fixing roller 37 as a fixing
member and a fixing guide 38 as a guide member. The sheet of paper
taken out from the paper feed cassette 4 or fed from the manual
feed mechanism 31 is carried along a longitudinal carrying path 34
via the resist roller 36 and the secondary transfer roller 27 to
the fixing unit 40.
[0024] A gate 33 is provided at the downstream of the fixing unit
40, and the sheets of paper are directed toward a paper discharge
roller 41 or a re-carrying unit 32. The sheet of paper guided to
the paper discharge roller 41 is discharged on the paper discharge
unit 3. Further, the sheet of paper guided to the re-carrying unit
32 is guided toward the secondary transfer roller 27 again.
[0025] Next, the fixing unit 40 will be described in detail. FIG. 2
is a schematic configuration diagram of the fixing unit 40 seen
from side. The fixing roller 37 has a heating roller 37a and a
pressing roller 37b. The heating roller 37a has a heater lamp 37c
in the hollow part inside. The pressing roller 37b is in contact
with the heating roller 37a by a pressurizing mechanism 37d at
predetermined pressure. Thereby, a nip 41 having a predetermined
width is formed between the heating roller 37a and the pressing
roller 37b.
[0026] The heating roller 37a is rotated in a direction of arrow q.
The pressing roller 37b is drivenly rotated in a direction of arrow
r due to pressure contact with the heating roller 37a. On the
periphery of the heating roller 37a, a first separating claw 42
that releases the sheet of paper P passing through the nip 41 from
the heat roller 37a is provided. Around the heating roller 37a, a
temperature detection element 44, a first cleaning member 46 and an
abnormal heating detection element 47 are provided at the
downstream of the first separating claw 42 along the rotational
direction of the heating roller 37a. On the periphery of the
pressing roller 37b, a second separating claw 43 for separating the
sheet of paper P from the pressing roller 37b and a second cleaning
member 48 are provided along the rotational direction of the
pressing roller 37b.
[0027] The fixing guide 38 is provided in the longitudinal carrying
path 34 from the secondary transfer roller 27 to the fixing roller
37. The fixing guide 38 guides the sheet of paper P on which the
toner image is transferred by the secondary transfer roller 27 to
the nip 41. As shown in FIG. 3 to FIG. 5, the fixing guide 38 has
plural rollers 50 as plural rotating members and a guide plate 51
as a supporting member that supports the rollers 50. The rollers 50
are supported by the guide plate 51 to rotate by sliding contact
with the sheet of paper P. The rollers 50 use BEAREE FE5101
manufactured by NTN corporation containing fluorine resin ETFE
(copolymer of tetrafluoroethylene and ethylene), for example.
[0028] The rollers 50 includes total three rows of rollers 52 in
the first row, rollers 53 in the second row and rollers 54 in the
third row, for example, along a direction of arrow t as the
traveling direction of the sheet of paper P. The rollers 50 are
arranged in eight rows, for example, in the width direction of the
sheet of paper P perpendicular to the direction of arrow t. The
diameters of the rollers 52 in the first row and the rollers 54 in
the third row are the same. The diameter of the rollers 53 in the
second row provided between the rollers 52 in the first row and the
rollers 54 in the third row is formed larger than the diameter of
the rollers 52 in the first row and the rollers 54 in the third
row. Note that the diameter sizes of the rollers in the three rows
are arbitrary and all of the rollers in the three rows may have the
same diameter.
[0029] All amounts of protrusion of the rollers 52 in the first row
to the rollers 54 in the third row from a supporting surface 51a of
the guide plate 51 are the same. Accordingly, the surface in
contact with the tops of the rollers 52 in the first row to the
rollers 54 in the third row (the surface indicated by dotted line
.alpha. in FIG. 4) is in parallel to the supporting surface 51a of
the guide plate 51. The fixing guide 38 guides the sheet of paper P
along the dotted line .alpha.. Thereby, the sheet of paper P is
guided to the nip 41. The amount of protrusion of the rollers 50
from the supporting surface 51a of the guide plate 51 is set to 1
mm, for example.
[0030] On the guide plate 51, ribs 56 in parallel to the traveling
direction of the sheet of paper P are provided. The ribs 56 are
integrated with the guide plate 51 by integral molding, for
example. As shown in FIG. 5, the height from the supporting surface
51a of the guide plate 51 to the tops of the rib 56 is lower than
the amount of protrusion of the rollers 50 from the supporting
surface 51a of the guide plate 51. The height from the supporting
surface 51a of the guide plate 51 to the tops of the rib 56 is set
to 0.5 mm, for example. The ribs 56 intervene between adjacent
rollers 50 in the width direction of the sheet of paper P and
support the curved part of the sheet of paper P. Thereby, in the
width direction, increase in curvature of the sheet of paper P and
occurrence of paper wrinkles are prevented.
[0031] Next, the operation of the guide unit 40 will be described.
An image formation process is started in the color copier 1. In the
image forming unit 11, toner images are formed on the
photoconductive drums 12Y, 12M, 12C and 12K by the image forming
stations 11Y, 11M, 11C and 11K of yellow (Y), magenta (M), cyan
(C), black (K), respectively. The toner images on the respective
photoconductive drums 12Y, 12M, 12C and 12K are sequentially
transferred onto the intermediate transfer belt 10 to form a
full-color toner image on the intermediate transfer belt 10.
[0032] The full-color toner image on the intermediate transfer belt
10 reaches the secondary transfer roller 27. In synchronization
with the full-color toner image on the intermediate transfer belt
10, the sheet of paper P is carried between the intermediate
transfer belt 10 and the secondary transfer roller 27. While the
sheet of paper P passes between the intermediate transfer belt 10
and the secondary transfer roller 27, the toner image on the
intermediate transfer belt 10 is transferred thereon. The sheet of
paper P supporting the toner image is guided toward the nip 41
position of the fixing roller 37 by the fixing guide 38.
[0033] In this regard, the sheet of paper P is not brought in
contact with the supporting surface 51a of the guide plate 51. The
sheet of paper P is guided along the surface indicated by the
dotted line a while being supported by the plural rollers 50
supported by the guide plate 51. Further, the plural rollers 50 are
rotated with traveling of the sheet of paper P in the direction of
arrow t. The sheet of paper P is supported not only by the rollers
50 but also by the ribs 56 according to its rigidity while being
guided to the fixing guide 38.
[0034] If the toner attached to the secondary transfer roller 27 at
secondary transfer adheres to the back of the sheet of paper P, the
rollers 50 do not rub off the toner on the back of the sheet of
paper P. The toner hardly adheres to the rollers 50 and the toner
attachment to the fixing guide 38 is suppressed. Further, even if
the toner adheres to the rollers 50, the rollers 50 slidingly
rotate in contact with the sheet of paper P and do not hinder the
traveling of the sheet of paper P in the direction of arrow t. That
is, jamming does not occur because of the sheet of paper P caught
by the toner attached to the rollers 50. Further, smudges on the
back do not occur because of offset of the toner attached to the
rollers 50 on the sheet of paper P. The sheet of paper P is guided
with high accuracy toward the nip 41 position of the fixing roller
37 by the fixing guide 38.
[0035] The sheet of paper P guided toward the nip 41 position is
nipped and carried by the heating roller 37a and the pressing
roller 37b, and the toner image is fixed by heating and pressure.
In this regard, there is no guide position shift of the sheet of
paper P due to the attached toner to the fixing guide 38, and thus,
image blurring and paper wrinkles at fixing do not occur.
[0036] After the toner image is fixed, the sheet of paper P is
discharged through the gate 33 to the paper discharge unit 3 by the
paper discharge roller 41 for single-side image printing.
[0037] For double-side image printing or multiple printing, the
sheet of paper P is re-carried to the secondary transfer part via
the re-carrying unit 32.
[0038] According to the embodiment, the sheet of paper P supporting
the toner image is guided to the nip 41 along the surface indicated
by dotted line .alpha. by the rollers 50 of the fixing guide 38.
The sheet of paper P is prevented from being in contact with the
guide plate 51. Thereby, toner attachment to the fixing guide 38
can be suppressed. The shift of the guide position of the sheet of
paper P due to the attached toner of the fixing guide 38 can be
prevented. The sheet of paper P is guided with high accuracy toward
the nip 41 position of the fixing roller 37. As a result, good
fixed images without image shift or paper wrinkles can be obtained.
Further, the smudges on the back of the sheet of paper P and
jamming due to the attached toner of the fixing guide 38 can be
prevented. Furthermore, the ribs 56 are provided to suppress the
curving of the sheet of paper P supported by the tops of the
rollers 50. Thereby, the curving of the sheet of paper P is
suppressed and occurrence of paper wrinkles at fixing is
prevented.
[0039] The invention is not limited to the embodiment and various
changes can be made within the scope of the invention. For
instance, the image forming apparatus may have any structure, and
the guide member may guide the recording member in the horizontal
direction. Further, the material and shape of the rotating member
is not limited. For example, it may be formed by a mold member and
a fluorine resin may be applied to the surface thereof.
Furthermore, the rotating member may not have a roller shape. For
example, as the first modified example shown in FIG. 6, rotating
members 62 supported by a guide plate 61 of a fixing guide 60 may
have star wheel shapes.
[0040] Moreover, the arrangement and number of the rotating
members, the number of ribs, and the like are not limited. For
example, the number of rows of rotating members along the traveling
direction of the recording medium is not limited to three. Further,
the number of rotating members in the width direction of the
recording medium is not limited to seven. As the second modified
example shown in FIG. 7, plural rollers 66 supported by a guide
plate 64 of a fixing guide 63 may be arranged apart. As the third
modified example shown in FIG. 8, ribs 70 may be provided in areas
with wide intervals if intervals between rotating members 68 of a
guide plate 67 are not uniform.
[0041] In addition, the amount of protrusion of the rotating member
from the supporting surface of the supporting member is not
limited. Note that, if the amount of protrusion of the rotating
member from the supporting surface of the supporting member is
greater, the curving of the recording member is greater and paper
wrinkles become easier to occur. On this account, the amount of
protrusion of the rotating member from the supporting surface of
the supporting member is desirably set to 1 mm or less. Further,
the height of the rib is not limited as long as it is lower than
the amount of protrusion of the rotating member. Furthermore, the
shape of the supporting member may be a frame shape, not the plate
shape as long as it rotatably supports the plural rotating
members.
* * * * *